Paleontologists have developed a new theory to explain why the ancient ancestors of dinosaurs stopped moving about on all fours and rose up on just their two hind legs.
Bipedalism in dinosaurs was inherited from ancient and much smaller proto-dinosaurs. The trick to this evolution is in their tails explains Scott Persons, postdoctoral fellow and lead author on the paper.
"The tails of proto-dinosaurs had big, leg-powering muscles," says Persons. "Having this muscle mass provided the strength and power required for early dinosaurs to stand on and move with their two back feet. We see a similar effect in many modern lizards that rise up and run bipedally."